(1) Field of Invention
The present invention relates to the field of breathing assistance devices.
(2) Description of Prior Art
Breathing aids or breathing assistance devices are well known in the art. Numerous devices have been disclosed which are designed to assist a patient who is having difficulty breathing. These devices often supply supplemental oxygen at a concentration higher than that in the atmosphere, and often under pressure, as a means of promoting improved respiration and/or improved oxygen absorption. Further, numerous breathing assistance devices which are designed to provide a continuous positive airway pressure (CPAP) have likewise been disclosed.
For example, U.S. Pat. No. 5,036,847, by Boussignac et al., discloses a breathing aid comprising a tubular main channel through which respiration occurs, with one end (proximal end) open to the atmosphere and at least one additional auxiliary channel opening into the main channel through which supplemental pressurized respirable gas (e.g. oxygen) is provided to the patient. The device produces a continuous positive airway pressure (CPAP). The invention of U.S. Pat. No. 5,036,847 also comprises a deflection face as a means to deflect the jet(s) of respirable gas exiting the auxiliary channel(s) towards the center of the main channel so that the jet(s) of respirable gas does not directly strike the patient's mucous membranes. Further, the disclosure also provides for an additional channel which opens into the distal end face (user end) of the tube and which may be connected to a pressure measurement device as well as a safety pressure relief device (perforations through the main tube in conjunction with a safety sleeve) to relieve pressure within the main tube in the event that the internal pressure becomes too high.
U.S. Pat. No. 5,538,002, U.S. Pat. No. 6,273,087, U.S. Pat. No. 6,363,935, U.S. Pat. No. 6,516,801, U.S. Pat. No. 6,761,172, and U.S. Pat. No. 6,814,075, as well as U.S. patent application Ser. No. 12/282,044, all by Boussignac (et al.), each likewise disclose similar inventions with various additional features. Many of these provide for a calibrated pressure relief valve in the proximal region of the main tube to relieve pressure in the main channel in the case of overpressure. Most of these require that the auxiliary channel(s) open into the main tube near (“close to,” “in proximity of,” “in the vicinity of”) the distal end of the device.
As another example, U.S. Pat. No. 5,193,532 by Moa et al., discloses a breathing assistance device which produces a continuous positive airway pressure by means of an ejector action due to the influx of supplemental respirable gas into a breathing channel through an inlet channel. This device, like the Boussignac devices referred to above, also exhibits a branch channel open to the atmosphere and is therefore not a closed circuit, ventilator type CPAP system. Further, in this device the breathing channel (first branch channel) and the exhaust channel (second branch channel) are not linearly aligned but rather form an angle of 30 to 50 degrees with one another.
U.S. Pat. No. 7,331,344, by Foster et al., discloses yet another example of a “breathing device” wherein supplemental respirable gas is provided into a breathing channel through an inlet channel. As in the above examples, the exhaust channel in this invention is open to the atmosphere. And here, once again, the breathing channel and exhaust channel are not collinear but rather form an oblique angle with one another. The inlet channel is laterally offset from the breathing channel so as to introduce supplemental respirable gas in such a manner that a “bypass” occurs, whereby some portion of the supplemental respirable gas goes directly to the exhaust channel. According to the author, “It has been recognized that the phenomena of jet bypass, whereby a proportion of the fresh gas supplied to the patient passes directly out of the exhaust tube is crucial in giving the low added work of breathing.” Col. 1, Lines 38-41.
Each of the above-described devices provide an exhaust channel open to the atmosphere yet provide a continuous positive airway pressure at the user end of the device. The use of continuous positive airway pressure both forces gas into the lungs during inhalation and forces the patient to exhale against pressurized gas during exhalation which may prevent the alveoli from collapsing. It has been found that in many cases, the use of such a CPAP device is of great assistance to patients experiencing breathing difficulties.